Yes, it is a moral issue. Your daughter is still a minor and will be for another 18 months. Not to mention all the *back* child support from when they were younger. How much all the parties to this arrangement are earning is entirely beside the point. If he wants to make up for being such a crap husband, let him do it the way that counts: by taking some financial responsibility, however little or late, for the children he chose to father. In fact, whether he wants to make up for being a crap husband or not, he still should take such responsibility as a co-parent. Don't make it easier for him to keep being a PAL. I have trouble believing you still have any cowishness left for his pathetic bedraggled whining puppy self, but that's kind of what it's reading like .....
OTOH, maybe that's what's making you so angry ....
"Show me a completely smooth operation and I'll show you someone who's covering mistakes. Real boats rock." -- Frank Herbert